"It's unreal. As a young boy in Australia, the Premier League is the main thing that everyone watches but nobody actually thinks they'll reach those heights," said Kuol.
"To be one of those people, to be in the position I am, it's amazing."
Newcastle reportedly paid an initial £300,000 before add-on clauses.
"He's very sharp, agile, quick, a good finisher," said Newcastle manager Eddie Howe.
"He's got a lot of very positive ingredients. That is going to be nurtured and developed in the next couple of years to get him at the right level for the Premier League.
"I met him for the first time in person yesterday. That was a very good conversation. He is a very confident, independent lad who has got high motivation."